<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      const user = {
        name: "jack",
        age: 20,
        "max age": 40,
      };
      console.log(user["name"]); //user.name
      console.log(user["age"]); //user.age
      console.log(user["max age"]);
      user["max age"] = 21; 
    </script>
  </body>
</html>
